This paper presents the results of two direct numerical simulations (DNS) carried out for turbulent pipe flow and heat transfer. The temperature is treated as a passive scalar, subject to isoflux boundary conditions and it turns out that energy conservation has to be enforced by means of a sink term in the energy equation. The finite volume algorithm used in this work guarantees global energy conservation at each time-step. The axis singularity is effectively circumvented by using fluxes instead of primitive variables, where needed. The preliminary results presented,
for both the velocity and the temperature fields, are in good agreement with available empirical correlations and past DNS studies, and this demonstrates the accuracy of our numerical method. Further simulations will be carried out on longer domains and/or with increased resolution.
